Two-stage fuel pump



Nw; 26,' 1940. A. c. KLECKNER TWO-STAGE FUEL PUMP Filed June 8, 1938 2Sheet-Sheet l WQ o ZZ 23 5.3

Nov. 26, 1940.

A. c. KLECKNER 2,223,070

TWO-STAGE FUEL PUMP Filed June 8, 1938 2 Sheets-Sheet 2 J3 jfl y gPatented Nov. 26, 1940 UNITED STATES PATENT OFFICE.I

TWO- STAGE FUEL PUBIP Arthur C. Kleckner, Racine, Wis., assignor, by

mcsne assignments, to Webster Electric Company, Racine, Wis., acorporation oi Delaware Application June 8, 1938, Serial No. 212,415

7 Claims.

takes advantage of the fact that a larger internal gear pump stage isadapted to pump an excess of liquid fuel over that pumped by a smallerinternal gear pump, which is one of the requirements for a two-stagegear pump of the type in which the first stage is merely used forbringing an excess supply of liquid fuel to the pump, and the secondstage produces the required pressure in a predetermined amount of liquidfuel for an oilburner or other device.

Another object of the invention is the provision of an improvedtwo-stage `gear pump which is adapted to be constructed moreeconomically than the devices of the prior art and which is adapted tobe used for a long period of time without necessity for any repair.

Another object of the invention is the provisin of an improved two-stagegear pump of the class described which is adapted to be self-priming andwhich vis adapted, therefore, to be used with oil burners under the mostadverse conditions of installation.

Other objects and advantages of the invention will be apparent from thefollowing description and the accompanying drawings, in which similarcharacters of reference indicate similar parts throughout the severalviews.

Referring to the two sheets of drawings accompanying this specification,

Fig. 1 is a diagrammatic view of the installation of the two stage gearpump in relation to a 5 supply tank;

Fig.v 2 is a sectional view in partial elevation on the plane of theline 2 2 of Fig. 3, looking in the direction of the arrows;

Fig. 3 is a vertical sectional view, taken on the plane of the line 3-3of Fig. 2, looking in' the direction of the arrows;

Fig. 4 lis another sectional view, taken on the plane of the line 4-4 ofFig. 2, looking in the direction of the arrows;

Fig. 5 is another sectional view, taken on the (Cl. 10S-126) plane ofthe line 5-5 of Fig. 2, looking in the, direction of the arrows;

Fig. 6 is a side elevational view of the pump, partially broken away, toshow the by-pass conduit;

. Fig. 7 is a sectional view, taken on the plane of the line 1-1 of Fig.3, showing the location of certain ports;

Fig. 8 is a view similar to Fig. 3, of a lmodiiied form of construction.

Referring to Fig. 1, this is a diagrammatic illustration in which thefuel supply tank I0 is provided with a supply of liquid fuel Il, such asoil, suitable for an oil burner, and the tank is provided with an intakepipe I2 leading to the intake' conduit of the pump I3.

The pump is provided with a by-pass outlet which is connected to theby-pass pipe I4, which leads back to the tank I Il and may dischargeabove or below'the surface of the supply of liquid fuel II.

The burner outlet conduit I5 communicates with the pump and leads to thenozzle of the oil burner, of which the pump I3 comprises a part.

For purposes of illustration, the pump is diag5 grammatically shown witha flexible drive IIiand an electric motor I1.

It should be understood that the present pump may be used in any oilburner installation, the usual installation including, not only themotor and pump and the flexible drive, but an air fan, suitable ignitionand safety devices, and the-conduits for air as well as fuel.

In order to include the illustrations in the minimum amount of space,some of the views show the gear pump inverted, or in a sidewiseposition, but the proper operating position is shown in Fig. 1, with theby-pass outlet I8 and by-pass conduit I4 at the top.

This by-pass conduit communicates with a fuel reservoir 20, 'from whichthe excess fuel is returned freely to the tank IIJ, and since the outletis at the top of the pump, the fuel reservoir will at all times beiilled with a supply of liquid fuel. Liquid fuel is thus available forpriming the pump at all times.

'I'he pump preferably comprises a` pump hous-`1 ing 2 I, which is formedwith a pump chamber 22 and a fuel reservoir 20, separated bya partition23. 'I'he pump housing 2| may be substantially cylindrical in shape, asshown in Fig. 2, and may have an axially extending wall 24 at one sideof Fig. 3, provided with an internal cylindrical surface 25, forming thepump chamber.

The adjacent surface 26 of the partition 23 y maybe a plane surface forengaging the fiat ends of the gears. The pump chamber is completed bymeans of a cover plate 21, which may consist of a cast metal member ofcircular shape and having adjacent its outer edge a plane seatingsurface 28, which is adapted to t against the p lane seating surface 29that is provided on the edge of the axially extending flange 24. Thesesurfaces may be lapped and ground to an accuratet.

The flange 24 has threaded bores 30 for receiving the screw bolts 3|,which pass through apertures in the cover plate 21 and are threaded inthe bores 30 to secure the cover plate on the housing 2 I.

The cover plate 21 is adapted to support a pair of integral, arcuatemembers or shields 32, 33, which are of sufficient depth to extend fromthe cover plate between the gears to the fiat surface 26, and bear aparticular relation to the gears of the pump, as will be described infull hereinafter.

The pump gears include an internal gear 34, another gear member 35,which is not only provided with `external spur teeth, but with internalteeth, and a pinion 36. The partition 23 is provided with a centrallylocated bore 31 adapted to receive, with a pressed frictional fit, abearing member 38 for the drive shaft 39.

The drive shaft 39 is rotatably mounted in the bearing 38 and is alsorotatably supported by a second self-lubricating bearing 40 ofthe typeconstructed of a porous bearing metal which has been soaked orimpregnated with lubricant.

'Ihe shaft 39 extends into a cylindrical aperture 4| in the pinion 36,pinion 36 being provided with oppositely located slots 42 for receivinga key 43. The key 43 may consist of a flat piece of metal which is alsovlocated in a complementary slot 44, formed in the end of the shaft 39.Thus the pinion 36 isl adapted to be rotated or driven by the shaft 39,which in turn is driven by the motor I1.

The arcuate shield 32, carried by the cover 21, has its innermostpartially cylindrical surface 45 formed with respect to the center oraxis of the shaft 39, which is indicated by the point 46. The outerpartially cylindrical surface 41 of the shield 32 is formed on a longerradius, which corresponds to the radius of the circle at the outer edgesof the teeth of the internal gear teeth of member 35.

'I'he center with respect to which this outer surface 41 is formed isindicated at 48.

It should be understood that all of the gear members herein arepreferably formed with helically or spirally extending teeth and bearingsuch a relation toward the outlets that the shape of the teeth tends toforce the liquid longitudinally of the gears, toward the proper outlet.

For the purpose of clarity and simplicity, however, the helical teethare not specifically illustrated in the drawings, which are toberegarded as diagrammatic in this respect.

,The radius of the internal cylindrical surface 45 is equal Ato theradius of a circle located at the outer edges of the teeth of thepinion36. Thus the arcuate shield or member 32 is adapted to fit inside yofthe internal gear teeth of the member 35 and outside the teeth of thepinion 36. Its length is slightly less than the intersection of the twocircles by means of which it is indicated, for the reason that it isundesirable to have sharp points on the shield 32, and betterconstruction at such a point that it covers a predetermined number oftooth depressions.

It is inherent in a construction of the type involving pinion 36 andinternal gears of member 35 that there must be more teeth in the largerinternal gear than there are in the pinion. Thus the pinion 36 has seventeeth, while the internal teeth on the gear member 35 number nine.

The shield 32 not only serves to cover a predetermined number of toothgrooves, but it also serves to keep the gear members in their properpositions in connection with the other shield 33, now to be described.

The gear member 35, which has external gear teeth and internal gearteeth, is adapted to be rotated by the pinion 36, and its teeth engagein the grooves between the internal teeth of the internal gear 34.

The internal gear 34 is adapted to be rotated by the gear member 35, andthus internal gear 34 slidably engages the cylindrical Wall 25 and theflat surfaces of the adjacent cover 21 and partition 23.

It should be understood that all of the gears and fiat or plane endsurfaces engage the complementary surfaces on the inside of the cover 21and the surface 26 on the partition 23. Furthermore, the width of thesegear members is such that there is a substantial t between the chamber22 of the gears; that is to say, a close sliding t, which is madefluid-tight by the presence of the liquid fuel, which also has somelubricating qualities.

In all gear pumps there is a certain amount of leakage or slippage ofliquid fuel past the gear teeth, and uid passes through the spaces atthe ends of the gears. That is also true in the present case, as it isnecessary to have the gears free for sliding motion in the chamber 22,in order to reduce friction.

The arcuate shield member 33 is so located inside of the cover 21 thatit is adapted to engage the outside of the teeth on gear member 35 andthe inside edges of the teeth on the internal gear 34.

This arcuate shield member has an internal, partially cylindricalsurface 49, which is formed on a radius that is equal to the radius ofthe circle located at the edges of the external teeth of the gear 35. yThe center with respect to which the cylindrical surface 49 is formed isthe center of the gear 35; that is, the point indicated at 48.

The external partially cylindrical surface 50 of the arcuate shield 33is formed on a radius which is equal to the radius of a circle locatedat the inner edges of the teeth of the internal gear 34. .f

The center with respect to this cylindrical surface 50 is formed in thecenter of the drive shaft,

indicated at the point 46.

In this case the arcuate shield 33 is again made shorter than thedistance between the intersecting points of the arcs 49'and 50, in orderthat it may be of suitable strength at its ends, and in order that itmay merely cover a predetermined number of tooth spaces; for example,four tooth spaces in the internal gear 34 are covered by the shield 33.

Whereas the gear member 35 has sixteen external teeth, the internal gear34, being larger, naturally has a larger number of inwardly projectingteeth, eighteen in number.

All of the gear members 34, 35, and 36 rotate together, being drivenfrom the same shaft; and,

involves the rounding olf of the ends 0f the shieldsince they operatelike a train of gears, the internal gear being the last in the train,there is no backlash or lost motion between the gears, which areconstantly driven in the same direction.

It will thus be observed that by means of these gear members there isprovision for two separate stages or pumps; that is, the pumping whichis accomplished between the teeth of the pinion 36 and internal teeth ofgear member 35, which may comprise one stage, and the pumping which isaccomplished between the external teeth on gear member 35 and theinternal teeth of internal gear 34, which may comprise another stage.

The two stages rotate at the same number of revolutions per minute, butthe outermost stage, or gear teeth, are larger in number, even if theyare of the same size, and therefore must pump a larger volume of liquidfuel.

It will thus be observed that I have provided 0 two stages, one of whichpumps an excess of fuel over the other, and I prefer to utilize thesetwo stages in such manner that the outermost stage is used as the firststage, pumping an excess of fuel, and the innermost stage is used as asecond stage, utilizing only what fuel it needs,

but producing the high pressure which is desired for an oil burner. Withthis in mind, I

shall now describe the location of the conduits by means of which theliquid is conducted to the proper points in the two stages of the pump.

It should be understood that while the gear members are shown havingteeth of substantially the same size, the teeth in the outermost stagemay be made of different size from the teeth in the innermost stage, orvice versa, providing, however, that in -each case the teeth whichintermesh must be of the same size.

The cylindrical housing 2l is provided with a pair of downwardlyprojecting lugs -4I, 52, and with an upwardly projecting lug 53' (Fig.1). These lugs are cored out to provide conduits, such as the by-passconduit I8, the inlet conduit 53, and the outlet conduit 54. Fig.4,.which is a section taken on the plane of the line 4--4 of Fig. 2,shows the inlet conduit 53, which extends into the partition 23, and isprovided with a laterally extending portion 55, terminating in the fiatface 26 in an aperture 56, shown in dotted lines.

This aperture 56 is located at the point where the teeth of the internalgear 34 begin to separate from the external teeth on the gear member 35,as these gears rotate in a counter-clockwise direction in Fig..2. Theport 56 then is the 1nlet port for the rst stage of the pump, and liquidfuel is sucked up through the conduit 53 into the spaces between theteeth 51, 58 and carried on around with the gear members 34 and 3 5 tothe discharge aperture 59, seen in dotted l1nes at the right of Fig. 2.'I'here the liquid is squeezed out from between the spaces between theteeth on account of the closer engagement of the teeth. The liquid does'not leak past and back of the teeth 51, 58 because at all times there isa sliding engagement between certain of the teeth 51, 58 or betweentooth 58 and the inner surface 49 of shield 33, or tooth 51y and theouter surface 50 of shield 33. The

aperture 59 is then the outlet aperture for the rst stage, and it isshown in Fig. 5 as being in communication with the reservoir 20.

The reservoir 26 is formed by an axially extending flange 60 carried bypartition 23, and

l it is closed by means of a gasket 6I and a. resilient diaphragm 62,both of which are clamped underneath another cover plate 63, by means ofscrew bolts 64.

The screw bolts 64 pass through the apertures in the cover plate 63, andare threaded into threaded bores in the ange 68. The diaphragm 62 hasthe centrally located aperture 65 for pass.. ing the shaft 39 and has ametal collar 66, which is provided with a plane surface 61 that has alapped or ground fit with a rib 68 carried by the collar 69.

The collar 69 is a tight frictional fit on the shaft 39, and thesurfaces on the collars 66 and 69 are held in tight engagement with eachother by the spring 10, which is compressed between the collar 66 and ahub 1I.

The spring 10 is of suicient size to be spacedy from the shaft 39, andit is held in place by the projecting bearing 38, which also serves tospace the spring from the shaft. A fiber washer 12 may be interposedbetween the collar 69 and the self-lubricating bearing 40, which isprovided with a thrust surface. A

'I'he cover plate 63 may also have a lubricant reservoir 13, which isfilled with a fibrous material 14, impregnated with semi-solid lubricantadapted to be fed to the porous bearing 48. The diaphragm 62 is thusadapted to prevent leakage of liquid from the reservoir 20, and theonlypoints of moving contact are those at engaging surfaces on the collars66 and 69, which may be provided with a lapped fit so that there ispractically no leakage past the spaces between these collars. In anyevent, the reservoir. 20 is, according to Fig. 6, which happens to beupside down. in communication with the by-pass conduit I8 that leads bymeans of conduit I4 directly back to the tank.

The first stage, therefore, merely keeps the reservoir 20 filled withliquid fuel, which is under no greater pressure than that involved bythe resistance of the by-pass pipe I4 leading back to the tank, and thepressure in the reservoir 20 is substantially atmospheric. Under theseconditions there is a tendency toward practically no leakage past thesealing collars 66, 69.

The intake port for the second stage, or smaller gears, is the aperture15, shown in dotted lines in Fig. 2, which, according to Fig. 4, is alsoin communication with the lower part of the reservoir 29. Since thisintake aperture extends from the lower part of the reservoir 20, thereis absolute assurance that intake port 15 of the second stage or highpressure gears will always be covered, so that the second stage4 will beself-priming. Liquid fuel enters at the port 15 into the intersticesbetween the teeth 16, 11 of the smaller gears and is carried on aroundto an outlet port 18. Outlet port 18 is formed in the cover plate 21,being a cored conduit which leads radially of the cover plate 21 andinside the cover plate to a port 19 that registers with a port 80carried by the pump body. The port 8Il,of the pump body communicateswith the outlet conduit 54 and is intended to be connected tothe pipeI5, which leads to the nozzle of the oil burner.

It will thus be observed that all of the inlet and outlet ports I8, 53,and 54 are provided with pipe threads so that they can be connected tothe pipes I2, I4, and I5.

The pinion 3s is, of course, heid in piace by v being mounted on theshaft 39 and by its engagement with the cylindrical surface 45 on thethe shield 33.

, 26 inside of the cover plate 2l.

, gagement of the outer cylindrical edges of its teeth with thecylindrical surface 49 on the shield 33. It is also held in place by theengagement of the inner cylindrical edges of its teeth l1 .with theouter cylindrical surface 61 on the shield 32.

The length of the shields 32, 33 is such that -they cover such an 'arcof such a number of teeth'or such a portion of the cylindrical edgesurfaces of the teeth that the lgears are positively held in properposition.

The operation of the gear pump will be evident from the foregoingdescription and explanation of the operation of its parts. The pinion 36is driven'by the shaft 39, which in -turn drives the gear member 35 byvirtue' of itsinternal teeth. The gear member 35 in turn drives theinternal gear 34. Thus the two stages of the pump are simultaneouslydriven, and the outer or first stage, having more teeth, is adapted topump more than the inner stage. The reservoir 2l). i's thus adapted tobe constantly lled'with an excess of liquid fuel, which is taken fromthe reservoir by the inner stage and delivered to a nozzle in suchvolume with respect to the nozzle capacity that a suitabl pressure isproduced.

It should be understood that in any gear pump the size of the gears inrelation to the nozzle capacity and the speed of rotation determines thepressure produced, disregardingl cer.

tain other minor factors.

Referring to Fig. 8, this is a modification in which the gear member 35is indicated by the numeral 35a to signify that it has been changed,

and it is provided with axially, inwardly extending annular grooves 85and 86, and the cover plate 21a is provided with an inwardly extendingannular rib 81, while the partition 23a hasan inwardly extending annularrib 88. The rib 88 has a sliding iit in groove 86, and rib 81 has asliding fit in groove 85. `Thus, in this case the gear member 35a isrotatably and slidably mounted on the ribs 81, 88, in addition to theother elements of the pump, holding this lgear member in place.

The shields 32 and' 33 are particularly adaptv ed to be machined witharminimum number of settings, because they are formed only upon twodifferent centers, and only two settings with respect to the centers arerequired. The present construction is simpler than the devices of theprior art, and therefore is adapted to perform its functions better.l

Due to the two-stage arrangement, this pump may be used as a fuel pumpWherever there is a heavy suction on the intake pipe or where there isliquid fuel under pressure applied to the intake pipe. Since the pump isself-priming, it will operate under all conditions,`and the first stageis practically self-priming because it does not pump against anysubstantial pressure. By the time the liquid fuel in the reservoir isexhausted, the rst stage will have primed itself completely, due to theremaining film of liquid fuel serving as lubricant on the gears, andWill have eliminated all air.

While I have illustrated a preferred embodiment of my invention, manymodifications may be made without departing from the spirit of theinvention, and I do not wish to be ylimited to the precise details ofconstruction set forth, but desire to avail myself of all changes withinthe scope of the appended claims.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United States is:

1. In a gear pump, the combination of a housing provided with a pumpchamber and bearings for a drive shaft, a drive shaft in said bearings,a driving gear carried by said drive shaft in said pump chamber andhaving external teeth and tooth spaces, a gear member carried in saidhousing surrounding said rstmentioned gear and having internal teeth,said gear member also having external teeth and a third gear memberrotatably mounted in said said pump, said housing also having arcuateshields between the teeth of said gear members for maintaining thealignment and location of said gear members, said housing being formedwith reservoir, and one of the stages of said pump. discharging intosaid reservoir,

`and the other of said stages having its intake port communicating withsaid reservoir.

2. In a gear pump, the combination of a houspump chamber and havingexternal teeth and 'Y tooth spaces, a gear member carried in saidhousing surrounding said first-mentioned gear and having internal teeth,said gear member also having external teeth and a third gear memberrotatably mounted in said housing and having internally extending teethfor engaging the second-mentioned gear member, said housing havingintake and outlet conduits extending to suitable points between theintermeshing teeth of said gear members whereby pumping is accomplishedin two stages in said pump, said housing also having arcuate shieldsbetween the teeth of said gear members for maintaining the alignment and.location of said gear members, said housing being formed with areservoir, and one of the stages of said pump discharging into saidreservoir, and the other of said stages having its intake portcommunicating with said reservoir, said reservoir having a free returnconduitto .the source of supply whereby it is at substantiallyatmospheric pressure, and said drive shaft extending through saidreservoir.

3. In a two-stage gear pump, the combination of a housing provided witha pump chamber and having -three gear members in said pump chamber, saidhousing having bearings for a drive shaft, and a drive shaft in saidbearings projecting into said pump chamber, said gear members comprisinga pinion carried by the drive shaft, a gear member having internal andexternal teeth, the internal gear teeth being engaged'by said pinion,and a gear member having internal teeth engaging the external teeth ofsaid second-mentioned gear member, said housing having intake and outletconduits communieating with the spaces between the intermeshing teeth ofthe two stages, and having arcuate members for maintaining coverage ofthe gear tooth spaces-and for separating the gear teeth during their,rotation a-t a predetermined point.

4. In a two-stage gear'pump, the combination of a housing provided witha pump chamber and having three gear members in said pump chamber, saidhousing having bearings for a drive shaft, and a drive shaft in saidbearings projecting into said pump chamber, said gear members comprisinga pinion carried by the drive shaft, a gear member having internal andexternal teeth, the internal gear teeth being engaged by said pinion,and a gear member having internal teeth engaging the external teeth ofsaid second-mentioned gear member, said housing having intake and outletconduits communicating with the spaces between the intermeshing teeth ofthe two stages, and having arcuate members for maintaining coverage ofthe gear tooth spaces and for separating the gear teeth during theirrotation at a predetermined point, the outlet from the first stage ofsaid pump being in communication with the vinlet of the second stage ofsaid Dump- 5. In a two-stage gear pump, the combination of a housingprovided with a pump chamber and having three gear members in said pumpchamber, said housing having bearings for a drive shaft, and a driveshaft in said bearings projecting into said pump chamber, said gearmembers comprising a pinion carried by the drive shaft, a gear memberhaving internal and external teeth,- the internal gear teeth beingengaged by said pinion, and a gear member having internal teeth engagingthe external teeth of' said second-mentioned gear member, said housinghaving intake and outlet conduits communicating with the spaces betweenthe intermeshing teeth of the two stages, and having arcuate members formaintaining coverage of the gear tooth spaces and for separating thegear teeth during their rotation at a predetermined point, the outletfrom the first stage of said pump being in communication with the inletof the second stage of said pump, through a reservoir, said reservoirbeing located about said drive shaft, and said drive shaft havingpacking located beyond said reservoir.

6. Ina two-stage gear pump, the combination of a metal housing formedwith a centrally located partition and a pair of axially extendingcylindrical anges, one of said cylindrical flanges forming a pumpchamber, and the other of said cylindrical anges forming a reservoir,said partition having a bearing, a drive shaft in said bearing, a coverplate Afor said pump chamber, a pinion carried by said drive shaft insaid pump chamber, and a second internal and external gear toothedmember surrounding and meshing with said-pinion in said pump chamber, aninternal toothed member surrounding and meshing with said second gearmemberv in said pump chamber, all of said gear members being driven fromsaid drive shaft, arcuate shields carried by said housing between theintermeshing teeth of said gear member, an intake conduit extending intosaid pump chamber in communication with the tooth spaces between the twooutermost sets of gear teeth, a discharge conduit extending from thetooth spaces between said gear teeth to said reservoir, an intakeconduit leading from said reservoir to'the gear tooth spaces between theteeth of the other intermeshing gears,and an outlet conduit extendingfrom the tooth spaces between said other intermeshing gears, saidreservoir having a cover plate through which said ,drive shaft extends.

shaft, a drive shaft in said bearing, a drivingA pinion concentricallycarried by said drive shaft in said pump chamber, and vhaving externalteeth and tooth spaces, an internally toothed gear member having anexternal cylindrical surface rotatably mounted in said housing andconcentrically rotatable in said housing, said cylindrical surfaceengaging the outer cylindrical wall of said housing, and a thirdfloating gear toothed member having internal and external teeth, andtooth spaces, the internal teeth of said floating member meshing withthe teeth of said driving gear, and the external teeth of said oatingmember meshing with the teeth of said internally toothed member, saidhousing having intake and outlet conduits for the space between thedriving gear and the floating member and for the space between thefloatingI member and the internally toothed member, and an arcuateshield between said driving gear and said fioating member for holdingthe external teeth of said oating member in engagement with the internalteeth of said internally toothed member, and covering predterminedtoothed spaces, and a second arcuate member located between said oatingmember and said internally toothed vmember, and covering predeterminedtoothed spaces.

ARTHUR C. KLECKNER.

vuo

